1. Field of the Invention
The present invention relates to a liquid fuel storage device including a fuel tank and a canister for use with a vehicle.
2. Description of Related Art
In order to fill-up a fuel tank with fuel smoothly, it is necessary that fuel vapor in the fuel tank be instantly emitted to the outside of the fuel tank to enable the fuel vapor to be replaced with the fuel without resistance. Further, since the fuel is vigorously ejected from a fuel gun inserted into a fuel port of the fuel tank in refueling, a lot of fuel mist is produced. Since the emission of fuel vapor and mist (hereinafter, referred to as "fuel gas") to the atmosphere causes an environmental problem, the fuel gas is generally introduced to a canister and adsorbed and captured thereby as in U.S. Pat. No. 5,090,459.
When refueling is necessary, since a fuel tank is usually almost entirely filled with a fuel gas, a large canister must be designed, taking the capacity of the fuel tank into consideration.
However, a large canister is not preferable to satisfy a trade-off request to increase the capacity of a fuel tank as well as the space in a vehicle.
To cope with this problem, a liquid fuel storage device for a vehicle has been proposed having a mechanism for inflating and deflating an air bag disposed in a tank according to a surplus space produced by an amount of storage fuel. This type of storage device has been disclosed, for example, in Japanese Patent Unexamined Publication No. 64-16426 (1989) wherein the space in a fuel tank filled with fuel gas (i.e., the space obtained by subtracting the amount of remaining fuel from the total capacity of the tank) can be reduced in refueling.
The fuel storage device arranged as described above usually requires pressurizing means (a pressurizing pump or the like) for pressurizing the air bag (by which the space occupied by the fuel storage unit as a whole is increased). Further, since the air bag communicates directly with the atmosphere to emit air in refueling, a fuel gas in the air bag which passes through an air bag film is simultaneously emitted.